Step 1: Cook the Pasta: Bring a large pot of salted water to a boil. Add macaroni and cook according to package instructions until just al dente. Drain and set aside.
Step 2: Make the Roux: In a large saucepan over medium heat, melt the butter. Whisk in the flour and cook for 1-2 minutes until bubbly (this forms a roux).
Step 3: Create the Béchamel: Gradually whisk in the milk and heavy cream, stirring constantly until smooth. Let it cook for about 5 minutes until slightly thickened.
Step 4: Add Seasonings & Cheese: Stir in salt, pepper, garlic powder, and paprika. Add 3 cups of cheddar and 1 cup of mozzarella, stirring until melted and smooth.
Step 5: Combine Pasta & Sauce: Add cooked macaroni to the cheese sauce and stir until well coated.
Step 6: Assemble & Bake: Pour half the mac and cheese into a greased 9x13-inch baking dish. Sprinkle with half of the remaining cheddar and mozzarella. Top with the rest of the mac and cheese, then finish with the remaining cheese.
Step 7: Bake to Golden Perfection: Bake uncovered at 375°F (190°C) for 20-25 minutes or until the top is bubbly and golden brown.
Step 8: Rest and Serve: Let rest for 5 minutes before serving for the creamiest texture.